Safety switch



3 Sheets-Sheet l A. CORBETT SAFETY SWITCH Filed Sept. 14, 1935 March 2, 1937.

March 2, 1937.

A. coRBETT 2,072,729

SAFETY SWITCH Filed sept. 14, 1955 s Sheets-sheet 2 4o 7 40a 38a.

INVENTOR March 2, 1937. A, CORBETT 2,072,729

SAFETY SWITCH Filed Sept. 14, 1955 I5 Sheets-Sheet 3 my INVENTOR M ATTORNEYS `Patented. Mar. 2, 1937 PATENT OFFICE SAFETY SWITCH Alfred Corbett, Irwin, Pa., assigner to National Electric Products Corporation, a corporation of Delaware Application September 14, 1935, Serial No. 40,605

13 claims.

y This invention relates to a safety switch, and particularly 4to a switch of the type which comprises fuses in electrical association with the switch contacts.

A primary object of my inventionl is to provide in a fuse-carrying switch assurance against injuryl to a person d ue to accidental bridging of live contacts in theswitch, under any circumstances. In explanation, itis an object of my invention to provide `a switch of this nature, in

which contacts through the switch may be either opened or closed without danger, and in which access may be had to fuses in the switch for removal or insertion of the fuses, likewise without 18 danger to the person performing the operation.

Another object of my invention is to Provide a fused safety switch in which the operation of making or breaking contact, or inserting or removing fuses, is simple, and in which circuits may be completed or opened through the switch without disturbing the position of the switch uses.

An additional object of my invention is to provide the advantages above noted in a fused safety switch which is structurally simple, which is compact, and which may readily be mounted within a switch cabinet.

A still further object of my invention is to provide in a fused safety switch of this nature such structural arrangement that the movable switching element of the"assembly may be physically detached in' opening circuits through the assembly. and may physically be reinserted in the assembly, without completing a circuit or circuits therethrough. y

In the accompanying drawings, Fig. I is a front elevation of a fuse or switch cabinet, showing in plan my improved safety switch mounted in the cabinet. Fig. II is a detailed side elevation 40 of one cover element of my safety switch assembly, showing attached thereto a specialized mounting for cartridge fuses and cartridge fuses positioned in the mounting structure. Fig. III

is an end elevation of the cover and fuse mounting assembly, which is shown in sid'elevation in llig.k 1I. Fig. IV is a side elevation of the other cover v element of my safety switch assembly,

showing `contacts mounted thereon, and illustrating that this second cover element is in speciilc function a switch element. Fig. V is an end elevation of the cover element and contacts car- A ri'ed thereby, which is shown in side elevation in ll'lg. IV. Fig. VI is a plan view of the receptacle of my safety switch assembly, adaptedto cooper- ,55 ate with the cover elements shown in Figs. II

(Cl. 20o-114) to V, inclusive. Fig. VII is a longitudinal sectional view taken on the section line VII-VH of Fig. VIII, through the safety switch assembly of my invention, showing both the fusing elements and the switching elements in operative or circuitclosing position. Fig. VIII is a cross-sectional view through the assembly, taken on the line VIII-V'III of Fig; VII. Fig. IX is a side elevation of my safety switch, showing the switching elements of the assembly mounted in the assembly in circuit-interrupting position, but with the fusing elements of the assembly remaining in position for the completion of a circuit through the fuses. In dotted lines this figure of the drawings illustrates the removal of the fuse-carrying cover element of the assembly from position in the receptacle. Fig. X is a plan view illustrating a modification in my safety switch assembly by means of which Vtwo circuits, controlled and fused in the safety switch, may be independently opened and closed, and by which access to the fuses of the two circuits for removal or insertion of a fuse may independently be had. Fig. XI is a side elevation of my safety switch, the view being partly broken away to show in vertical section a modification in the mounting of the switch-carrying cover element of the assembly on the receptacle. Fig. XII is a fragmentary plan view of the receptacle modified in accordance with the showing of Fig. XII.l Fig. XIII is anl end view of the fuse-carrying cover element of the assembly, i1- lustrating a modification in the mounting of the handle on the body of the cover and a modification in the attachment of the fuse-carrying bracket to the cover. Fig. XIV is a vertical section through the fuse-carrying cover element, taken on the plane XIV-XIV of Fig. XIII.

Referring to the drawings, reference numeral I designates a hinged-lid metal cabinet of usual type, suitable for containing my fused safety switch; and in Fig. I of the drawings reference numerals 2 and l designate generally and respectively my fused safety switch and the live electrical connections therewith. A neutral bar la is also shown, connected at one end of the switch. In Fig. I it will be seen that the basal or receptacle element l of my switch assembly carries two separate cover elements 5 and t.

Referring indiscriminately to Figs. II to VIII, i, inclusive, of the drawings, in describing the structural details of my safety switch, the basal element t of the switch is in the form of a rec'- tangular receptacle body of porcelain or other suitable insulating material, having side walls 'l and end walls l and la. Embraced.between the side walls 1, one end wall 8, and a transverse partition wall 9, having a particular function hereinafter to be described, there is a fuse-receiving cavity I of irregular contour.

Extending toward each other in the cavity I6 there are a pair of longitudinally projecting and vertically extending stub walls II and I2. Floor portions I3 and I4 extending beyond the end walls and 8a provide for the mounting of live 10 circuit terminals I5, I5a and I6, Ia. Extension I4 provides also for the mounting of a neutral bar 3a, as shown in Fig. I. Reference must be had to Fig. I of the drawings for a showing of terminals I5a and I6a, as in Fig. VII these terminals are obscured, respectively, by the terminals I5 and I6.

Referring speciilcally to Figs. II and III of the drawings, the fuse-carrying cover element therein shown is adapted to rest upon the upper surfaces of the receptacle walls, substantially to cover the cavity I6 of the receptacle. Dependently mounted on the under face of cover element 5 is' an insulating body I1. Integrally formed with the body Il are two laterally extending trough members I8, which may be, as shown, substantially U-shaped in end elevation. Desirably, as shown, trough members I8 are of a length suitable to receive the fiber intermediate portion of a cartridge fuse I 9, with the ferrules I 9a of the fuses lying immediately beyond the terminal edges of the trough members. As so mounted, the shoulders of the fuse ferrules I9a,

lying adjacent the terminal edges of the trough members, serve to define the longitudinal,

' 35 mounted position of the fuses.

Spacing bars 20, of insulating material, are formed integrally with, or are permanently attached to, the body of the cover element, to depend from the under face thereof in position 40 to contact, or lie clo'sely adjacent, the intermediate, insulated regions of the fuses. To remove and replace fuses, the cover element 5 is removed from receptacle 4, and screws 2|, which connect the fuse-mounting body to the body of the cover element, are retracted to permit the withdrawal or insertion of fuses at the interval between the-upper edges of the trough members"v I8, and the lower edges of the spacing bars 20. After removing a blown fuse in this manner, a live fuse may be inserted, and may be clamped in position merely by tightening the screws 2I.

It will be noted that the assembly of the cover, and the fuse mounting structure, is such that the cartridge fuses are embraced wholly by bodies of insulation, and that the use of spring vclips of conducting material in the fuse mounting is avoided. The cover and fuse mounting assembly presents for the making of contact only the metallic ferrules I9a, which form elements of the cartridge fuses. No additional contact is carried at the underface of the cover, nor is there presented by it any metal member capable l of making accidental contact. c5 By placing the cover element 5 in proper position on the receptacle 4, the ferrules I9a of the cartridge fuses I9 are brought into engagement with two pairs of longitudinally spaced contact clips 22, 22a and 23, 23a, which are mounted on the receptacle floor underlying cavity III. Referring to Fig. VII of the drawings, it will be noted that the contact clips 22 and 23 have direct electrical connection with the terminals I5 and I5a. rIhe electrical connection of contact clips 22a and 23a with terminals I6 and I 6a is indirect. and

will be hereinafter specifically described. These several contacts and terminals are not all'to be found in any single iigure of the drawings. All the terminals are, however, shown in Fig. I, and the yterminals I5 and I6 are shown in Fig. VII. In Fig. VII the contacts 22 and 22a also appear, while the contacts 22 and 23 are shown in Fig. VIII. The contact 23a, being obscured in both Fig. VII and Fig. VIII, is specially shown in Fig. VI. 10

During insertion of cover element 5 in cavity II] of the receptacle, the fuse ferrules are guided into their cooperating spring clips by engagement of the lateral edges of fuse-mounting troughs I8 in relatively shallow, vertical grooves 15 24, in the inner faces of the receptacle side walls l. In circuit-making position of the fuses, with their ferrules engaged by the spring clips of the receptacle, the fuse-mounting body I'I lies between the terminal edges of the stub walls II and I2, so that the cavity In of the receptacle is in elect divided into two longitudinal chambers by cooperating bodies of insulation.

It should be explained that there is no guiding cooperation between the edges of the fstub; 25 walls and the fuse-mounting structure, the cooperation between the edges of trough members I8 and the grooves 24 in the side walls of the receptacle maintaining these elements in spaced relation. The body of cover 5 overlies the walls ,i130 of the receptacle and the upper faces of the stubs walls Il and I2, the cover and-fuse-mounting structure as a whole being held positively in the receptacle by the engagement of the fuses I9 in the spring clips of the receptacle.

Mounted in the floor of the receptacle underlying cavity Ill, is a pair of :spring contact forks 25 and 26, placed on opposite sides of stub wall I2, and between fuse clips 22a and 23a,.,and the partition walls 9. Cooperating spring contacts 40 25a, and 26a lie in restricted chambers 2l, beitween partition walls 9, and the rear wall Bai :of the receptacle. These pairs of spring contacts 25, 25a and 26, 26a, are the switch contacts of the assembly. The contacts 25 and 26 have elec- 45 trical connection with fuse clips 22a and 23a, and the switch contacts 25a and 26a have electrical I connection with the terminals I6 and.v I6a. In order to complete connection to the fuses it is, therefore, necessary to interconnect switch con- 50 tacts 25 and 25a, and on the other sideV of the receptacle to interconnect switch contacts 26 and 26a. y i

Interconnection of the spring contacts, providing the switch contact elements of the recep-i 55 tacle, is effected by means of the second cover element 6. This second cover element 6, which is in eiect a switch plug, has mounted yat the under face thereof two U-shaped contact members 28 and 28a, having, respectively, a pair ofwo spaced blades 29 and 29a. The body of the cover element is of insulating material, and has swingingly .mounted on the upper surface thereof a handle or bail 3U. i

To complete circuits through the assembly g5 the fuse-carrying cover element in position to make the circuits. between the fuse clips of the receptacle and the ferrules of the cartridge fuses carried by the cover, circuit is completed by placing the second cover element 6 in position on the 70 receptacle, so that its contact blades 29 bridge the switch contacts 25 and 25a, and its contact blades 25a.' bridge switch contacts 26 and 26a. In so interconnecting the spring switch contacts of the receptacle, the contact elements carried by the cover 6 bridge over the transverse partition-walls 9 in the cavity of the receptacle.

Cover element 5 is rabbeted along its rearward edge at 3 I, and the forward edge of the cover element 6 is undercut, to provide a forwardly extending rib 32, fitting the rabbeted region 3l at the rearward edge of the cover element 5. When, therefore, the fuse-carrying cover 5 and the switch cover 6 are placed in circuit-completing position on'the receptacle, shoulder 32 of the switch cover, lying in rabbet 3| of the fuse cover, and overlying a flange 33 formed thereby, must be removed before fuse cover 5 may be removed. In order to render itincreasingly difficult to remove fuse cover 5 without first removing switch cover 6, the .handle of the fuse cover is in the form of a bail 34, swingingly mounted in a depression 35 of the fuse cover, by means of a bracket 3,6, mounted in the depression by means of the screws 2 I, which connect the fuse-carrying assembly to the cover. Bail 34 surrounds a bossv 35a in the depression 35 (see Figs. I and III),

which boss renders it difficult to grasp bail k34 adjacent its hinged terminal, and the free terminal of the bail 34 may lie in a depression 33a formed in the ange 33 at the rearward edge of the fuse cover. With bail 34 lying against the cover element 5, as shown inl Figs. II and VII,

and with switch cover 6` in circuit-completing position, shoulder 32 on the switch cover overlies the free terminal of bail 34, so that it cannot be grasped without first removing thefuse cover.

Because of this arrangement, the switch cover 6 must be removed from circuit-completing position, and the circuits through the assembly broken before the fuse-carrying cover element 5 may be removed from the receptacle. There is, therefore, no danger involved in removing cover 5 to replace a blown fuse, since all the contacts on the fuse-containing side of partition walls 9 are dead. There is no possible risk of accidentally bridging the switch contacts of the receptacle,

because of the restricted area of the chambers 21- in which switch contacts 25a and 26a are mounted. It may be noted'that, in my fused switch assembly, It is unnecessary to disturb the position of the fuses in order to complete or interrupt the circuits through the assembly, since a complete switching action is obtained by making or breaking contact between the pairs of blades 29 and 29a of cover 6, and the spring contacts in the receptacle with which they cooperate.

In order that the switch cover 6, and its contacts, may not be mislaid or iniured when it isv removed Vto interruptV the circuits through the assembly, I provide in the receptacle means for retaining the switch cover assembly in circuitinterrupting position therein. To this end I provide vertical slots 38 and 33a in a partition wall 9, and in the end wall 8a of the receptacle, and provide at the other side of the receptacle similarly formed and positioned slots 39 and 39a.

The slots of each cooperative pair are spaced apart a distance substantially equal to the space between the contact blades carried by the switch cover. The sockets are formed in the porcelain, or other insulating material, of the receptacle body, and are closed at their lower extremities, so that the switch blades, when inserted in the slots, are out of contact with, and are shielded from, any conductive material.

In breaking the circuits through the assembly, switch cover 6 is lifted from its -position interconnecting the receptacle switch contacts 25, 25a and 26, 26a, and is reinserted with its blades 29 in the slots 39 and 33a, and with its blades 29a in the slots 39 and 39a. Switch cover 6 is thus physically supported by the receptaclebody in an inoperative, circuit-interrupting position.

Referring to Fig. IX of the drawings, it will be seen that the shoulder 32 on switch cover 6 is of such width that, whenthe switch cover is reinserted in circuit-interrupting position, the rearward edge of fuse-carrying cover 5 may clear it. The free terminal of bail 34 of the fuse cover 5 being also exposed by this position of the switch cover, the cover element 5 may readily be lifted from its position on the receptacle.

It will be noted that the structure is compact, and, further, that it presents a pleasing appearance in plan view, whether the switch cover element be in circuit-completing or circuit-interrupting position. It is in the highest degree a safety switch, since all the contact elements of the assembly, when live, are fully shielded against accidental bridging. For some uses my fused safety switch presents features of particular convenience, as it may readily be used as a circuit-control switch without disturbing the receptacle is provided with a fuse-carrying cover i 4I, and contact-carrying, or switch cover, 4Ia. This arrangement provides for the completion and interruption of the circuits at the two sides of the assembly independently, and provides independently for the replacement of a fuse in either of the circuits. Such independent control of the two circuits presupposes the connection of a neutral bar at the terminal -42.

In Fig. X switching cover 40a is shown in lcircuit-completing position overlying the flange and bail of fuse-carrying cover 40, and exposing that one, 38a, of its dead sockets which is formed in the rear wall of the receptacle. The switching cover 4in is shown mounted in circuit-interrupting position, in which its/contact blades lie in the dead sockets 39 and 39a, exposing the bail on the fuse-carrying cover element 4I, and clearing. the rearward extremity of that cover element.

Referring to Figs. XI and XII of the drawings, illustrating modified mountings of the switchcarrying cover on the receptacle, reference numeral 43 designates the receptacle of the switch assembly, and reference numerals 44 and' 45 designate respectively the fuse-carrying cover element and the switch-carrying cover element of the assembly. In order that the switching cover may not be placed upon the receptacle in reversed position, a. cooperating groove and lug are formed at one side only-of 'the assembly. As shown, the lug 46 is formed on the under face of cover element 45, in position to enter groove 41 in the wall of the receptacle when the cover element is placed in proper position thereon. Groove 41 is 0f such length that the lug 46 may lie in it in either circuit-completing position or circuit-interrupting position of the cover element. While the Aillustration is of a lug on the cover element, and a groove in the receptacle wall, it is to be understood that the groove and lug may f .50 is attached to the cover proper by a connecting screw 5I. As shown, the screw 5I is threaded into a nut 52 lying at the underside of the central insulating body a, instead of into the handle-mounting plate 48a. This arrangement has advantage in the appearance of the switch assembly, in that it presents to view the head, rather than the shank terminal, of the mounting screw.

I claim as my invention:

1. In a fused safety switch the combination of a dished receptacle element having therein a pair of relatively spaced fuse-receiving contacts, one of said fuse-receiving contacts having connection to a terminal and the other having conriection to one of a cooperative pair of switch contacts, a cover element carrying ruses in position to bridge the said fuse-receiving contacts in mounted position of the said cover element on the receptacle, and a second cover element carrying thereon means adapted to inalre connection between the said pair of switch contacts.

2. In a fused safety switch the combination of a dished receptacle element having therein a pair relatively spaced fuse-receiving contacts, one or said fuse-receiving contacts having connection to a terminal and the other having connection to one of a cooperative pair of switch contacts, a cover element carrying fuses in position. to bridge the said fuse-receiving contacts in mounted position of the said cover element on the receptacle, and asecond cover element carrying thereon means adapted to make connection bctween the said pair of switch contacts, said cover elements as positioned tc close the receptacie having an interlocking engagement obstructing removal ci the inse-carrying cover element withont rst removing the switching cover element CII rn circuit-completing position on the receptacle.

3. a fused safety switch the combination of a dished receptacle having therein a pair of reiatively spaced ruse-receiving contacts, one oz said fuse-receiving contacts having connection- .a dished receptacle having therein a pair ci relatively spaced fuse-receiving contacts, oney of said fuse-receiving contacts having connection to a 'terminal and the other having connection to one of a cooperative pair oi relatively spaced switch contacts having an insulating wall therebetween, a cover element carrying fuses in position to bridge the said fuse-receiving contacts in mounted position of the said cover element on the receptacle, a second cover element carrying infuse and switch contacts in the receptacle cooperatively arranged with respect to the covercarried fuse and cover-carried switch to complete a circuit through the assembly with both cover elements positioned on the receptacle.

6. In a fused safety switch the combination of a dished receptacle with separate fuse-carrying and switch-carrying cover elements therefor, and fuse and switch contacts in the receptacle cooperatively arranged with respect to the covercarried fuse and cover-carried switch to complete a circuit through the assembly with both cover elements positioned on the receptacle, said cover elements having interlocking engagement arranged to obstruct removal of the fuse-carrying cover element from position on the receptacle without prior removal of the switch-carrying element from circuit-completing position on the receptacle.

7. In a fused safety switch the combination of a dished receptacle having therein a pair oi relatively spaced fuse-receiving contacts, one of said fuse-receiving contacts having connection to a terminal and the other having connection to one of a pair oi relatively spaced switch contacts having an insulating wall therebetween, a cover element carrying fuses in position to bridge the said fuse-receiving contacts in mounted position ci the said cover element on the receptacle, a second cover element carrying interconnected contact blades adapted to bridge the cooperative switch contacts on opposite sides ci? insulating wali, and dead sockets in the receptacie spaced trom each other a distance adapted to reception of the said contact blades for mounting the contact-carrying cover element on the receptacle circuit-interrupting po ii. in a :fused safety switch the cor a dished receptacle hav, g therein p tively spaced fuse-receiving contacts, on. of said. fuse-receiving contacts having connection to a terminal and the other having connection to one of a pair relatively spaced switch contacts have ing an insulating wali therebetween, a cover einient carrying fuses in position tov bridge the said inse-receiving contacts in mounted position. of the said cover element on the receptacle, a second cover eiernent carrying interconnected contact blades adapted to bridge the cooperative switch contacts on opposite sides of said insulatine wail, dead sockets in the receptacle spaced from each other a distance adapted to the reception of 'the said contact blades for mounting the contact-carrying cover element on the receptacle in circuit-interrupting position, said cover elements as positioned to close the receptacle having an interlocking engagement obstructing removal ci the fuse-carrying cover element withont first removing the switching cover element from circuit-completing position on the receptacle.

` 9. lin a fused safety switch the combination of a dished receptacle with separate fuse-'carrying and switch contact-carrying cover elements therefor, fuse and switch contacts in the receptacle cooperatively arranged with respect to the cover-carried fuse and contacts to complete a circuit through the assembly with both cover elements positioned on the receptacle, and non-conduotive members in the receptacle arranged to receive and engage the switch contacts carried by the one cover element thereby to mount the said cover element in circuit-interrupting position on the receptacle.

10. In al fused safety switch the combination of a dished receptacle with separate fuse-carrying and switch contact-carrying cover elements therefor. fuse and switch contactsin the receptacle cooperatively arranged with respect to the cover-carried fuse and contacts to complete a circuit through the assembly with both cover elements positioned on the receptacle, non-conductive members in the receptacle arranged'to receive and engage the switch contacts carried by the one cover element thereby to mount the said cover element in circuit-interrupting position onthe receptacle, said cover elements as positioned to close the'receptacle having an interlocking engagement obstructing removal of the fuse-carrying cover element without first removing the switching cover element from circuit-completing position on the receptacle.

11. In combination with a switch cabinet having an opening giving access to the switch and a closure element for said cabinet a fused safety switch comprising a dished receptacle element, a cover element carrying fuses arranged to complete circuits through 'the receptacle. and a switch-carrying cover element arranged in alternative mounted positions on the receptacle respectively to complete and to interrupt said circuits. said switch-carrying cover element in both of its alternative positions lying wholly within the height of the cabinet and permitting closure thereof.

12. In combination with a switch cabinet having an opening giving access to the switch and a closure element for said cabinet, a fused safety switch comprising a receptacle and a 4cover element mountable on the receptacle in alternative positions in a single horizontal plane butin different vertical planes, said cover element being arranged respectively to complete and to Ainterrupt a circuit through the receptacle in its different alternative positions and in both positions lying wholly within the height of the cabinet to permit closure thereof.

13. yIn a fused safety switch the combination of a dished receptacle having therein a pair of relatively spaced fuse contacts, one of said contacts having connection to a terminal and the other having connection to one of a pair of cooperative switch contacts, a cover element carrying contacts relatively spaced to cooperate with the i'use contacts of the receptacle in mounted position of the cover element on the receptacle, one of the said contact pairs having fusible electrical connection therebetween, and a second cover element carrying thereon means adapted to make connection between the said pair of switch contacts, said cover elements as positioned to close the receptacle having an interlocking engagement obstructing removal of the cover element cooperating to make fusible connection in the receptacle without first removing the switching cover element from circuit-completing position on the receptacle.

lALFRED CORBE'IT. 

